Originally Posted by
UA_Flyer
I meant to say "Unusual to me, because I have not observed this particular flight path after more than a dozen or so IAD-NRT-IAD flights.
The plane took off from NRT and followed pretty much the same flight path as NRT-SFO, and then somewhere north of SFO (within CA airspace) it turn into a typical SFO-IAD transcon path.
Most of the NRT-IAD path I have observed are:
Plane goes north towards the polar area then come down through Canada, and then enters the US space somewhere north of the Midwest region.
Has anyone experience the same flight path I have experienced yesterday?
In addition to the other explanations already posted, it could be an issue with air mass temperature. Polar routes sometimes pass through EXTREMELY cold air which lowers the fuel temperature to at or below the freeze point. In the event the low temps are forecast, the flight will be routed around the 'offending' air mass. The 400 is a little better in this situation since it can fly faster than the 777 and increase the aerodynamic heating, thus lowering the fuel temp (just a little...). The 400 also has better flexibility at flying lower or higher to avoid the cold air mass. IIRC, the 777 that flamed out on approach to LHR was a victim of fuel icing.